Desiderius was a Gallo-Roman dux

Dux

Dux is Latin for leader and later for Duke and its variant forms ....

in the Kingdom of the Franks during the reigns of Chilperic I

Chilperic I

Chilperic I was the king of Neustria from 561 to his death. He was one of the sons of the Frankish king Clotaire I and Queen Aregund....

 and Guntram

Guntram

Saint Guntram was the king of Burgundy from 561 to 592. He was a son of Chlothar I and Ingunda...

. He served Chilperic as Duke of Aquitaine

Duke of Aquitaine

The Duke of Aquitaine ruled the historical region of Aquitaine under the supremacy of Frankish, English and later French kings....

 and was his greatest general.

When Sigebert I

Sigebert I

Sigebert I was the king of Austrasia from the death of his father in 561 to his own death. He was the third surviving son out of four of Clotaire I and Ingund...

 of Austrasia

Austrasia

Austrasia formed the northeastern portion of the Kingdom of the Merovingian Franks, comprising parts of the territory of present-day eastern France, western Germany, Belgium, Luxembourg and the Netherlands. Metz served as its capital, although some Austrasian kings ruled from Rheims, Trier, and...

 died in 575, Chilperic sent Desiderius to invade his kingdom, but Guntram of Burgundy sent the patrician Mummolus

Mummolus

Mummolus, Mommolus, or Mummulus, born Eunius to one Peonius, Count of Auxerre. He was a Gallo-Roman patrician and prefect who served Guntram, King of Burgundy, as a general....

 against him and Desiderius was defeated and forced to retreat, leaving Austrasia to Sigebert's son Childebert II

Childebert II

.Childebert II was the Merovingian king of Austrasia, which included Provence at the time, from 575 until his death in 595, the eldest and succeeding son of Sigebert I, and the king of Burgundy from 592 to his death, as the adopted and succeeding son of his uncle Guntram.-Childhood:When his father...

. The following year, with the armies of Bladast

Bladast

Bladast or Bladastes was a Frankish dux during the reigns of Chilperic I and Chlothar II.In 583 or 581, Chilperic I gave the province of Aquitaine to Bladast and Desiderius and sent them into Vasconia with the Aquitainian army. They were defeated....

 and Berulf, surrounded the territory of Bourges

Bourges

Bourges is a city in central France on the Yèvre river. It is the capital of the department of Cher and also was the capital of the former province of Berry.-History:...

. They subsequently devastated the Touraine

Touraine

The Touraine is one of the traditional provinces of France. Its capital was Tours. During the political reorganization of French territory in 1790, the Touraine was divided between the departments of Indre-et-Loire, :Loir-et-Cher and Indre.-Geography:...

, as recorded by the then bishop of Tours, Gregory

Gregory of Tours

Saint Gregory of Tours was a Gallo-Roman historian and Bishop of Tours, which made him a leading prelate of Gaul. He was born Georgius Florentius, later adding the name Gregorius in honour of his maternal great-grandfather...

, the historian.

In 583, Chilperic gave the province of Aquitaine

Aquitaine

Aquitaine , archaic Guyenne/Guienne , is one of the 27 regions of France, in the south-western part of metropolitan France, along the Atlantic Ocean and the Pyrenees mountain range on the border with Spain. It comprises the 5 departments of Dordogne, :Lot et Garonne, :Pyrénées-Atlantiques, Landes...

 to him and Bladast and sent them into Vasconia

Vasconia

Vasconia is an historical name derived from the ancient tribe of the Vascones and used in different times, specially in the Middle Ages, to refer to the Basque territories...

 with a large army. They were defeated and most of the army destroyed.

When Chilperic died (584), Desiderius went to Toulouse

Toulouse

Toulouse is a city in the Haute-Garonne department in southwestern FranceIt lies on the banks of the River Garonne, 590 km away from Paris and half-way between the Atlantic Ocean and the Mediterranean Sea...

 to secure the treasure imparted to Chilperic's daughter Riguntha, betrothed to Reccared

Reccared

Reccared I was Visigothic King of Hispania, Septimania and Galicia. His reign marked a climactic shift in history, with the king's renunciation of traditional Arianism in favour of Catholic Christianity in 587.Reccared was the younger son of King Liuvigild by his first wife Theodosia...

, son of Leovigild, King of Spain. The next year (584), Desiderius made peace with Guntram, but two years after that (587), he died. His widow Tetradia, daughter of a noblewoman and a peasant, was taken to court by her former husband Eulalius, from whom she had fled with a large portion of his fortune. The stolen property was returned to Eulalius and Desiderius' children by her were delegitimised.

Sources

• Gregory of Tours
  Gregory of Tours
  Saint Gregory of Tours was a Gallo-Roman historian and Bishop of Tours, which made him a leading prelate of Gaul. He was born Georgius Florentius, later adding the name Gregorius in honour of his maternal great-grandfather...
  
  . Historia Francorum. translated Earnest Brehaut, 1916.
• Lewis, Archibald R. "The Dukes in the Regnum Francorum, A.D. 550-751." Speculum, Vol. 51, No 3 (July 1976), pp 381–410.